CMSIS-DSP  Verison 1.1.0
CMSIS DSP Software Library
Functions
Vector Inverse Park transform
Controller Functions

Functions

__STATIC_INLINE void arm_inv_park_f32 (float32_t Id, float32_t Iq, float32_t *pIalpha, float32_t *pIbeta, float32_t sinVal, float32_t cosVal)
 Floating-point Inverse Park transform.
__STATIC_INLINE void arm_inv_park_q31 (q31_t Id, q31_t Iq, q31_t *pIalpha, q31_t *pIbeta, q31_t sinVal, q31_t cosVal)
 Inverse Park transform for Q31 version.

Description

Inverse Park transform converts the input flux and torque components to two-coordinate vector.

The function operates on a single sample of data and each call to the function returns the processed output. The library provides separate functions for Q31 and floating-point data types.

Algorithm
parkInvFormula.gif
where pIalpha and pIbeta are the stator vector components, Id and Iq are rotor vector components and cosVal and sinVal are the cosine and sine values of theta (rotor flux position).
Fixed-Point Behavior
Care must be taken when using the Q31 version of the Park transform. In particular, the overflow and saturation behavior of the accumulator used must be considered. Refer to the function specific documentation below for usage guidelines.

Function Documentation

__STATIC_INLINE void arm_inv_park_f32 ( float32_t  Id,
float32_t  Iq,
float32_t *  pIalpha,
float32_t *  pIbeta,
float32_t  sinVal,
float32_t  cosVal 
)
Parameters:
[in]Idinput coordinate of rotor reference frame d
[in]Iqinput coordinate of rotor reference frame q
[out]*pIalphapoints to output two-phase orthogonal vector axis alpha
[out]*pIbetapoints to output two-phase orthogonal vector axis beta
[in]sinValsine value of rotation angle theta
[in]cosValcosine value of rotation angle theta
Returns:
none.
__STATIC_INLINE void arm_inv_park_q31 ( q31_t  Id,
q31_t  Iq,
q31_t *  pIalpha,
q31_t *  pIbeta,
q31_t  sinVal,
q31_t  cosVal 
)
Parameters:
[in]Idinput coordinate of rotor reference frame d
[in]Iqinput coordinate of rotor reference frame q
[out]*pIalphapoints to output two-phase orthogonal vector axis alpha
[out]*pIbetapoints to output two-phase orthogonal vector axis beta
[in]sinValsine value of rotation angle theta
[in]cosValcosine value of rotation angle theta
Returns:
none.

Scaling and Overflow Behavior:

The function is implemented using an internal 32-bit accumulator. The accumulator maintains 1.31 format by truncating lower 31 bits of the intermediate multiplication in 2.62 format. There is saturation on the addition, hence there is no risk of overflow.